Aircraft electrical systems usually include electrical components, devices, equipment, etc. that require certain power quality characteristics. For example, certain electrical components may not function properly if there are electrical disturbances in the DC power supply. Electrical disturbances can include a wide range of phenomenon, including power interruptions, high voltage transients, low voltage transients, ripple voltages, and more.
The power quality characteristics experienced during testing can vary dramatically from those experienced during actual aircraft operation. During testing, the DC power can be provided by a programmable power supply in a highly regulated and stable environment. During actual aircraft operation, however, the DC power is usually derived from an AC generator coupled to an engine that is operating at variable speeds, from which the AC power is transformed, rectified, filtered, etc. The variable nature of this operation, as well as other factors, can result in DC power that exhibits less than ideal power quality characteristics.